Entity Design Skill

Choose the correct identity type:

• GuidEntity for client-side generated UUIDs
• SerialEntity for database auto-increment IDs
• Entity<T> for custom ID types

Create public constructor with all required fields including:

• id, createdAt, updatedAt, isActive
• All domain-specific fields

Add creation factory (e.g., .create()) that:

• Generates appropriate ID using GuidEntity.newId() or SerialEntity.unsavedId
• Sets createdAt and updatedAt to current time
• Sets isActive: true by default
• Initializes entity in valid state

Protect internal collections:

• Use private fields with underscore prefix
• Return List.unmodifiable() from getters
• Never expose mutable collections directly